The 3rd Generation Partnership Project, 3GPP, is responsible for the standardization of the Universal Mobile Telecommunication System, UMTS, and Long Term Evolution, LTE. The 3GPP work on LTE is also referred to as Evolved Universal Terrestrial Access Network, E-UTRAN. LTE is a technology for realizing high-speed packet-based communication that can reach high data rates both in the downlink and in the uplink, and is thought of as a next generation mobile communication system relative to UMTS. In order to support high data rates, LTE allows for a system bandwidth of 20 MHz, or up to 100 MHz when carrier aggregation is employed. LTE is also able to operate in different frequency bands and can operate in at least Frequency Division Duplex, FDD and Time Division Duplex, TDD, modes.
In 5G, i.e. 5th generation mobile networks, there will be evolvement of the current LTE system to 5G. The main task for 5G is to improve throughput and capacity compared to LTE. This is achieved by increasing the sample rate and bandwidth per carrier. 5G is also focusing on use of higher carrier frequencies i.e. above 5-10 GHz.
One main object of a 5G radio concept is to support highly reliable ultra-low delay Machine-Type Communication, MTC, i.e., Critical-MTC. The Critical-MTC concept should address the design trade-offs regarding e.g., end-to-end latency, transmission reliability, system capacity and deployment, and provide solutions for how to design a wireless network for different industrial-application use cases. The Critical MTC system should in particular allow for radio resource management that allows the coexistence between different classes of applications: sporadic data, e.g., alert messages, periodic data, and others with e.g. real-time data (or simply best-effort data).
One approach is to mix C-MTC applications with ordinary Mobile Broadband, MBB, traffic on the newly defined 5G. Hence, similar random access procedures as well as scheduling request procedures may be used for C-MTC applications as for MBB service, however with much tighter latency requirements/response times and/or reliability requirements.
Alert messages e.g., alarms is probably one important type of messages that needs support for critical MTC application. Alarms are typically rare events. Hence, the alarm may be of Random Access type in some cases while in other cases, where we can assume that wireless device has reasonable sync to the network node, a scheduling request may be used.
In many automation scenarios it might be likely that alarms come in clusters. That means, once a sensor is transmitting an alarm it is likely that other sensors may transmit alarms almost at the same time or very short time after the first alarm. A simple example of such type of alarm is the temperature/smoke alarm that could simultaneously trigger several closely spaced sensors. The alarms or alerts may come in the order of milliseconds, and then the network might not be able to detect the alarm message(s) with possible fatal problem/failure as a potential cause.
In any case, the system needs to be designed such that rare alarm events may be transmitted with very low latency and detected with high reliability.
One simple prior art solution for avoiding such risk for collisions is to allocate separate frequency/time resources for random access/scheduling request to all sensors sufficiently often in order to fulfill the latency requirements. However with that approach significantly amount of resources need to be pre-allocated that typically would not be used and hence very low system capacity is achieved.
Another approach is to use a high complexity detector algorithm, however using such an algorithm for monitoring rare events may imply that a lot of hardware capacity in the receiving network node, also referred to as message detector, is allocated to the complex detector algorithm instead of serving ordinary cellular traffic in the system, giving reduction in the system capacity, or increased cost for the hardware and/or software in the network node to maintain simultaneously high capacity system and high complexity detector.
However, it is desirable being able to handle clustered alarm situations in a good way such that the high reliability detection is maintained at the same time as an acceptable false alarm rate is achieved and complexity of the detector is maintained on an acceptable level.